Exhaust gas recirculation (EGR) systems are used in internal combustion engines to reduce emissions and increase combustion efficiency. The exhaust gas flowing through the EGR system may flow through a heat exchanger, such as an EGR cooler. The EGR cooler may function to reduce the exhaust gas temperature before entering the intake manifold, thereby increasing density of the air entering the engine and thus increasing engine power and improving fuel efficiency. Further, cooled air may lower combustion temperatures and aid in controlling certain engine emissions. However, under certain conditions, such as during engine cold start, condensate may form within the EGR cooler. The condensate may accumulate in the EGR cooler and may then be swept to the engine. A small volume of condensate may not effect engine functioning, while a larger volume of condensate may cause engine misfire and may reduce the effectiveness of the EGR cooler over time. Further, in EGR coolers, which cool exhaust being recirculated back to the intake, acidic compounds may be present in the condensate, resulting in degradation to the cooler and/or downstream components.
To prevent the accumulation of condensate within the heat exchanger, a bypass line may be provided around the heat exchanger. During conditions in which condensate is predicted to form in the heat exchanger, the air normally provided to the heat exchanger may be routed through the bypass line to avoid possible deposition of condensate within the heat exchanger. However, such bypass lines may be expensive and increase the complexity of the engine control system strategy. Further, it may be difficult to accurately predict when condensation may form, resulting in unnecessary bypass of the air and increased temperature and decreased density of the air.
The inventors have recognized the issues with the above approach and offer a system to at least partly mitigate the problem of excess condensate generation in EGR coolers. One embodiment for a system includes an engine coupled to an intake system and an exhaust system, an exhaust gas recirculation (EGR) system coupling the exhaust system to the intake system, and an EGR cooler positioned in the EGR system, the EGR cooler having an inlet coupled to the exhaust system, a first outlet coupled to the exhaust system, and a second outlet coupled to the intake system, the second outlet positioned vertically higher than the first outlet.
In this way, the condensate accumulated in an EGR cooler may be directed through the first outlet towards the exhaust system, thereby preventing the condensate from exiting through the EGR cooler second outlet, which connects to the intake manifold of the engine and is vertically higher than the first outlet. Flowing the condensate from the EGR cooler towards the exhaust system and preventing the condensate from entering the engine may reduce engine combustion problems, including engine misfire.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.